Among flat display apparatuses, Thin Film Transistor Liquid Crystal Displays (briefly, TFT-LCDs) are characterized by small volume, low power consumption, relatively low cost of production, low radiation, and the like, and predominate in the current market of flat displays.
During the manufacture of TFT-LCDs, a color film substrate and an array substrate need to be bonded together for cell assembly, wherein the bonding material as used is a frame-sealing adhesive. The frame-sealing adhesive serves not only to bond the array substrate and the color film substrate, but also to seal the liquid crystal. Thus, the frame-sealing adhesive is an essential material in the cell assembly process of liquid crystal panels.
Currently, frame-sealing adhesives are primarily composed of epoxy resin-based adhesives, hydrophobic micron-sized silica filler spheres, catalysts, and catalyst solvents. During the process of UV radiation curing and thermal curing, the polymerization of adhesives will result in various degrees of hole and punctures in the frame-sealing adhesive, thereby causing defective problems including air bubbles, contamination, and the like. The lack of the frame-sealing adhesive during the process of coating will directly lead to the loss of product. Thus, a special detecting device should be arranged at the downstream of the coating apparatus for the frame-sealing adhesive to monitor the coating circumstance of the frame-sealing adhesive, so as to avoid the occurrence of a large number of defects. In the current detecting apparatus for the frame-sealing adhesive, the analysis for defecting the frame-sealing adhesive depends primarily on visual observation under microscope which has relatively low precision.